Conventional in-wheel motors for electric vehicles consist of those described below.
FIG. 1 is a sectional view showing the structure of a conventional in-wheel motor for an electric vehicle.
FIG. 1 shows an in-wheel motor that is configured such that the casing of a motor, which partially constitutes a drive mechanism, includes mounting means. In this electric vehicle, a drive mechanism 100 is integrally incorporated into a driving wheel (in-wheel-motor type). The drive mechanism 100 is configured such that a drive motor 200, a reduction gear mechanism 300, and a brake 400 are integrated into a unit mechanism. A tire 500 is mounted on the unit mechanism.
The drive motor 200 is a permanent-magnet-type AC motor. A casing 210 of the drive motor 200 is composed of an outer frame 211, an inner frame 212, an end ring 213, and an end plate 214. The outer frame 211 is cylindrical and includes a bracket portion 211a, which is located towards the right in FIG. 1. The inner frame 212 is a cylindrical member that is concentrically disposed within the outer frame 211, and includes a bracket portion 212a, which is located at the right end in FIG. 1.
The bracket portion 211a and the bracket portion 212a are joined via bolts, whereby the outer frame 211 and the inner frame 212 are joined. The end ring 213 and the end plate 214 are attached via bolts to the left end face of the outer frame 211.
A stator 220, which includes a stator core 221 and a coil 222, is mounted on the inner circumferential surface of the outer frame 211. A cylindrical rotor 240 is rotatably mounted on the outer circumferential surface of the inner frame 212 via a motor bearing 230.
The rotor 240 includes a rotor core 241 and a permanent magnet 242. A rotary block 250 is attached to the rotor core 241 via bolts. A revolution speed detector 260 is attached to the left-hand end of the rotary block 250. A shaft 270 is serration-coupled to a right-hand portion of the rotary block 250. AC current is supplied to the coil 222 of the drive motor 200 through a cable 280. A revolution speed signal indicative of revolution speed detected by the revolution speed detector 260 is output through a cable 281.
Support rings 290 and 291 formed in the outer frame 211 are fitted to corresponding fulcrums of a suspension mechanism, whereby the drive mechanism 100 is mounted onto a chassis of the electric vehicle.
The reduction gear mechanism 300 is a planetary gear mechanism and is adapted to transmit rotation of the shaft 270 to a wheel shaft 410 after reduction of speed. In this case, a carrier 301 of the reduction gear mechanism 300 is serration-coupled to the wheel shaft 410 so as to transmit torque to the wheel shaft 410 while being allowed to move axially.
A wheel shaft tube 411, through which the wheel shaft 410 extends, is fixedly attached to the bracket portions 211a and 212a. The reduction gear mechanism 300 is disposed in a space that is enclosed by the wheel shaft tube 411 and the bracket portion 212a of the inner frame 212. A ring gear 302 of a planetary gear is formed on the inner surface of the inner frame 212. An end face of the shaft 270 and an end face of the wheel shaft 410 are pivoted by means of a pivot 412. The brake 400 is a hydraulic brake that uses a drum.
A wheel hub 420 is attached to the wheel shaft 410 via bolts. A brake drum 430 and a disk wheel 505 of a wheel are attached to the wheel hub 420 via bolts. A hub bearing 440, which serves as a wheel bearing, is interposed between the wheel shaft tube 411 and the wheel hub 420. A back plate of the brake 400 is fixedly attached to a flange portion of the wheel shaft tube 411. When hydraulic pressure increases as a result of a brake pedal being stepped on, a wheel cylinder 401 causes brake shoes 402 to be expanded, so that the brake shoes 402 come into contact with the brake drum 430 for braking.
The tire 500 is mounted on a rim 510 of the disk wheel 505. In the thus-configured drive mechanism 100, when the motor 200 is activated to thereby rotate the rotor 240, rotation of the rotor 240 is transmitted to the rotary block 250 and the shaft 270 and is then speed-reduced at the reduction gear mechanism 300. The speed-reduced rotation is transmitted to the wheel shaft 410. Thus, the tire 500 coupled to the wheel shaft 410 is rotated, whereby the electric vehicle moves.
FIG. 2 is a modified version of the drive mechanism 100 shown in FIG. 1. For application to a small-diameter tire 500, this modified drive mechanism employs a drive motor 200 having a long axial dimension and a short radial dimension. Since the drive motor 200 has a short radial dimension, centrifugal force induced by the rotor 240 is small, and thus the drive motor 200 can be a high-speed motor.
Therefore, the reduction gear mechanism 300 is designed to provide a large reduction gear ratio; thus, the outside diameter of the reduction gear mechanism 300 is greater than the inside diameter of the stator 220. Also in this embodiment, the ring gear 302 of the reduction gear mechanism 300 is formed on the inner surface of the inner frame 212.
Still another drive mechanism is disclosed in U.S. Pat. No. 5,087,229. This drive mechanism includes a drive motor, a reduction gearset, a brake, and a tire as well as a steering knuckle, a ball joint mechanism, etc. which are provided integrally with a motor wheel for supporting the motor wheel.
In FIG. 3, reference numeral 10 denotes a motor wheel; reference numeral 12 denotes a steering knuckle; reference numeral 14 denotes a ball joint mechanism; reference numeral 16 denotes a motor wheel support element; reference numeral 18 denotes a vehicle shock tower; reference numeral 20 denotes a frame member; reference numeral 22 denotes bolts; reference numeral 24 denotes a mounting clamp; reference numeral 26 denotes a McPherson assembly; reference numeral 28 denotes a plate; reference numeral 30 denotes a nut; reference numeral 32 denotes a lower control arm; reference numeral 34 denotes a sway bar; reference numeral 36 denotes a ball joint mechanism; reference numeral 38 denotes a link; reference numeral 40 denotes a hub; reference numeral 42 denotes bolts; reference numeral 44 denotes a motor housing; reference numeral 46 denotes bolts; reference numeral 48 denotes a housing of a planetary reduction gearset assembly; reference numeral 49 denotes a gearset; reference numeral 50 denotes bolts; reference numeral 51 denotes a steering tie rod attached to the steering knuckle 12; reference numeral 52 denotes a hub bearing element; reference numerals 53 and 54 denote bearings; reference numeral 58 denotes a disk rotor; reference numeral 60 denotes a disk wheel; reference numeral 62 denotes lug nuts; reference numeral 64 denotes a tire; reference numeral 66 denotes a valve; reference numeral 68 denotes a caliper; reference numeral 72 denotes pads; reference numeral 76 denotes cooling fins; reference numeral 80 denotes a stator; reference numeral 82 denotes a coil; reference numeral 84 denotes lead-in conductors; reference numeral 86 denotes a connector; reference numeral 88 denotes a cable; reference numeral 90 denotes a driving shaft; reference numeral 91 denotes a washer; reference numeral 92 denotes a hub nut; reference numeral 93 denotes a rotor; reference numeral 94 denotes a rotor; reference numeral 95 denotes magnets; and reference numeral 96 denotes a rotation detector.